Catalytic reduction of nitric oxide in the presence of oxygen in low concentration high velocity gas streams

A small fixed‐bed catalytic reactor and a gas chromatographic analytical method were used to investigate the effects of oxygen on nitric oxide reduction by hydrogen over metal alloys. This work follows similar investigations, previously reported, into the reduction of nitric oxide with hydrogen in the absence of oxygen. The rate of oxygen consumption was directly proportional to hydrogen concentration but independent of oxygen concentration, at oxygen and hydrogen partial pressures of 4 — 7 × 10 −3 atm., and 1 — 11 × 10 −3 atm., respectively, and space velocities of 43,000 – 45,000 hr −3 . The activation energy for Monel* alloy was 8.8 kcals* g* mole −1 over a temperature range 347 – 502°C In comparing Monel and brass catalysts some selectivity in the reduction of nitric oxide in the presence of oxygen was observed. Depending on the conditions to which Monel has been subjected, its activity at a given temperature was found to vary with time from one level to another.